Control system for a blade-wheel propeller

ABSTRACT

A blade-wheel propeller for a ship has pilot control means for operation of servo motors which displace a control column and are actuable from a remotely located control stand. A first pivotable servo shaft is operatively connected to the pilot control means and is connected to a rectilinear motion transmission means which includes a first pivot pin on a rectilinearly guided portion thereof. A second servo shaft is operatively connected to the pilot control means and is pivotally connected by a radius rod to the rectilinear motion transmission means. There are further provided means responsive to the position of the first pivot pin for operating the servo motors to position the control column to coincide with the pivot pin. A correction transmission in the form of a parallelogram joint is connected to the rectilinear motion transmission means and causes the central control disk to approach the neutral position along an approximately elliptical path.

United States Patent Fork [ CONTROL SYSTEM FOR A BLADE- [45] Oct. 24, 1972 WHEEL PROPELLER Primary Examiner-Everette A. Powell, Jr. [72] Inventor: Werner Fork, Bremen-Artsen, Ger- A't0mey Edmund Jasklewlcz [57 ABSTRACT [73] Asslgnee' g ga g GmbH Heldenhelm A blade-wheel propeller for a ship has pilot control means for operation of servo motors which displace a [22] Filed: June 14, 1971 control column and are actuable from a remotely [2]] App] No 152 731 located control stand. A first pivotable servo shaft is operatively connected to the pilot control means and is connected to a rectilinear motion transmission Foreign Application Priority Data means which includes a first pivot pin on a June 18 1970 Germany up 20 29 9961 rectilinearly guided portion thereof. A second servo shaft is operatively connected to the pilot control 52 us. c|... ..416/111 means and is Pivmally mnemd by a radius 51 Int. Cl. ..B63h 1/10 the transmissb" means- There are [58] Field of Search ..4l6/l08 110 111 further Pmvided means reslmsive the first pivot pin for operating the servo motors to [56] References Cited position the control column to coincide with the pivot pin. A correction transmission in the form of a paral- UNITED STATES PATENTS lelogram joint is connected to the rectilinear motion transmission means and causes the central control disk 3,241,618 3/1966 7 Baer ..4l6/l08 UX 10 approach the neutral position along an approxi FOREIGN PATENTS OR APPLICATIONS mately elhptlcal p 898,406 HI 1953 Germany .i ..4l6/108 9 Claims, 13 Drawing Figures .1 I I6 22 m a 6 7 l l0 .11

r 2 9 HT r3 mgmmum 24 m2 3. 700.349

saw 1 BF 5 Fig. 3 39 35 50 39 PATENTED 24 I97? 3 700 349 SHEET 5 OF 5 CONTROL SYSTEM FOR A BLADE-WHEEL PROPELLER The present invention relates to a control system for a ship blade-wheel propeller, more particularly, to an apparatus responsive to a remotely located control station for operating the servo motors to control the direction of thrust of the propeller.

A blade-wheelpropeller of the type known as the Voith-Schneider propeller comprises a disk shaped wheel body rotatably mounted in a propeller housing which is firmly attached to the body of a ship. A plurality of blades extend vertically downwardly from the wheel body adjacent its periphery with the blades being pivotable about their longitudinal axes. The blades are each connected by driving rods to a central control disk which is adjustably positionable within the wheel body so. that its center may be eccentrically positioned with respect to the rotary axis of the propeller. Upon each rotation of the propeller the blades will be oscillated about their respective longitudinal axes. When the central control disk has its center positioned on the axis of rotation of the propeller so as to be in the neutral position each blade is positioned substantially tangentially to a blade circle which passes through longitudinal axes of the blades. The magnitude of oscillation of each blade is determined by the distance between the center of the control disk and the axis of rotation of the propeller with the deflection of each blade being calculated from its displacement from its tangential position. The similar oscillating movements of the blades produce a directed stream of water or thrust in a direction which is substantially perpendicular to a plane passing through the axis of rotation of the propeller and the center of the control disk or the center of eccentricity.

A control column is pivotably mounted in its central portion by being spherically supported in the neck of the propeller housing cover so as to be tiltable in all directions. The control column is coaxial to the axis of rotation of the propeller when it is in its vertical rest position. The lower end of the control rod is provided with a spherical head which is pivotally connected to the control disk and the upper end is similarly provided with a spherical head which is pivotally connected in a bearing sleeve coupled to the moveable components of a pair of servo motors positioned on the propeller housing at right angles to each other. The movement of the servo motors is thus directly transmitted to the lower end of the control column to correspondingly position the control disk.

The servo motors are operated by two pilot control means which can be actuated from a remotely located point such as a control stand which is usually positioned on the bridge of a ship. In ships having two or more blade-wheel propellers the operating systems for all of the propellers can be combined in a single control stand.

Each pilot control means comprises a pair of control members which are displaceable relative to each other and may comprise a control piston slideable in a control housing. Either the piston or the housing may be fixed and the other member coupled to the control stand. Th coupling may be mechanical, hydraulic, pneumatic, or electrical. The moveable member of each pilot control means is coupled to the slideable component'of the associated servo motor through a restoring lever by means of which the moveable control member is returned into its middle or neutral position after the slideable part of the servo motor reaches the position corresponding to the position selected on the control stand.

The control system for a blade-wheel propeller generally employes one servo motor for adjusting the distance of the control disk from the axis of rotation of the propeller in a direction corresponding to straight travel both forwardly and rearwardly. The other servo motor displaces the control disk in a transverse direction which is almost identical to a rotation of the control disk positioned ata distance from the axis of rotation of the propeller so as to vary the direction of thrust from the propeller with respect to the longitudinal axis of the vehicle. As a result, there is a change in the course of the ship when the ship is travelling straight ahead. The use of one servo motor together with a control stand travelling lever to control straight travel of the ship in a forward or rearward direction and the use of the other servo motor with a control stand steering wheel to control the direction of thrust of the propeller are advantageous with respect to the operation of a ship but present serious problems with respect to the construction and operation of the control system.

One disadvantage of the two servo motor control system as described above is that both servo motors of each blade-wheel propeller must assume a position which is precisely defined with respect to the ship. The precise position of the servo motors which are mounted in the propeller housing can be determined only when the jet direction of the propeller corresponding to optimum propulsion conditions in straight forward travel is defined with respect to the longitudinal axis of the ship. However, this optimum directional thrust can normally be determined only by conducting extensive tests on a model of the ship. Even after such tests have been completed it is usually discovered during the trial run of the completed ship that some adjustment must be made in the installation position. of the blade-wheel propeller. It would be desirable. for a blade-wheel propeller to be so constructed that adjustment of the direction of thrust for straight forward travel may be varied on the installed propeller without the necessity of altering structurally the propeller or the ship.

A further disadvantage of the control system as described above results from the connections of the piston rods of the servo motors, which are fixedly mounted on the propeller housing, to the upper ball head of the control column by links. Thus, the operation of one servo motor while the piston of the other servo motor is stationary, causes the upper ball head of the control column to move along a circular are having a radius equal to the length of the connecting link of the stationary servo motor piston. As a result, the central control disk is also displaced along a corresponding circular arc. This means that actuation of only one servo motor piston varies not only the intensity of the jet of water delivered by the propeller but also its direction.

It is therefore the principal object of the present invention to provide a novel and improved control system for a blade-wheel propeller mounted on a ship.

It is another object of the present invention to provide a control system for a blade-wheel propeller which is reliable in operation without any increase in its structural complexity.

The objects of the present invention are achieved and the disadvantages of the prior art are eliminated by the control system for ship blade-wheel propellers as disclosed herein. In such a control system there is generally provided a disk shaped wheel body rotatably mounted in a propeller housing and having a plurality of blades extending vertically downwardly adjacent its periphery with the blades being pivotable about their longitudinal axes. A central control disk is adjustably positioned within the wheel body and is connected by linkage to the blades whereby the blades are oscillated during each revolution of the propeller. The magnitude of the deflection of the blades during their oscillatory movement is determined by the distance between the axis of rotation of the wheel body and the center of the control disk. The oscillation of the blades produces a thrust in a direction perpendicular to a plane passing through the axis of rotation of the wheel body and the center of the control disk. A control column is mounted for universal tilting movement about its center and has its lower end pivotally connected to the control disk and its upper end pivotally connected to a pair of servo motors mounted on the propeller housing at right angles to each other. The movement of the servo motors will displace the upper and lower ends of the column transversely with respect to the axis of rotation of the propeller. Two pilot control means which are actuable from a remotely located control stand have moveable components connected to the servo motors for operation of the servo motors. According to the present invention there is disclosed a first pivotable servo shaft which is operatively connected to the pilot control means and a rectilinear motion transmission means including a first pivot pin on a rectilinearly guided portion thereof connected to the first servo shaft. A second servo shaft is operatively connected to the pilot control means. A radius rod pivotally connects the rectilinear motion transmission means and the second servo shaft. Means are provided which are responsive to the position of the first pivot pin for operating the servo motors.

The control system as disclosed herein requires a relatively simple structure which nevertheless assures that the upper ball head of the control column and, accordingly, the central control disk, is displaced along a straight line whose direction is associated with the direction of travel of the ship when the ship is proceeding along a straight path. In contrast to previously known control systems when the central control disk is being displaced along a straight line both servo motors in the present invention will always be operated. Both servo motors are simultaneously operated in response to the rotation of a single servo shaft in response to actuation of a control lever on a remotely located control stand. The actuation of a second servo shaft will move the control disk transversely to the above mentioned straight line to change the course of the ship either independently of the magnitude of displacement of the control disk along the previously mentioned straight line or dependent upon the magnitude of such displacement. Thus the second servo shaft can be operatively coupled to the steering wheel of the control stand. The blade-wheel propeller according to the present invention can thus be operated in the usual manner from a control stand which is provided with a control lever for fore and aft control of the ship and a steering wheel to change the course of the ship.

The rectilinear motion transmission linkage may be supported by means of the two servo shafts in a structural component mounted on top of the propeller housing cover or on the propeller housing cover itself.

The rectilinear motion transmission may comprise three transmission links positioned in a Z-shaped configuration and pivotally connected at their ends. The two outer transmission links are identical in length and are positioned parallel to each other with the first pivot pin of the joint being positioned in the center of the middle transmission element equidistant from the pivotal connections on both ends thereof.

A multi-link correction transmission comprising a parallelogram joint is interposed into the driving linkage for the control valves of the servo motors to automatically reduce the pitch of the blade-wheel propeller a degree which prevents overloading of the prime mover.

Other objects and advantages of the present invention will be apparent upon reference to the accompanying description when taken in conjunction with the following drawings, which are exemplary, wherein:

FIG. 1 is a diagrammatic elevational view of a ship blade-wheel propeller assembly incorporating the control system according to the present invention;

FIG. 2 is a top plan view of the rectilinear motion transmission of the present invention and viewed along the plane 11-11 of FIG. 3;

FIG. 3 is an elevational view of the rectilinear motion transmission shown in FIG. 2 viewed in the direction of the arrows P-P of FIG. 2.

FIG. 4 is a view similar to that of FIG. 2 but showing a correction transmission connected to the rectilinear motion transmission which is in the neutral position and viewed along the plane IV-IV of FIG. 5;

FIG. 5 is an elevational view of the transmission shown in FIG. 4 and taken in section along the line V V of FIG. 4;

FIG. 6 is an elevational view of the correction trans mission shown in FIG. 4 and taken along the section VI-VI of FIG. 4;

FIG. 7 is an elevational view of a portion of the correction transmission of FIG. 4 taken along a sectional line VII-VII;

FIG. 8 is a view similar to that of FIG. 4 and showing the rectilinear motion transmission in a position removed from the neutral position both with respect to fore and aft travel of the ship and to a change of course of the ship;

FIG. 9 is a view similar to that of FIG. 8 but showing the mechanism displaced a small angular distance with respect to the position of the mechanism in FIG. 8;

FIG. 10 is an elevational view of the rectilinear motion transmission of FIG. 9 taken in section along the line X-X;

FIG. 11 is a top plan view of a correction transmission modified from that shown in FIGS. 4-10 and taken in section along the line XI-XI of FIG. 12;

FIG. 12 is an elevational view of the control system of FIG. 11 and taken in section along the line XII-XII of FIG. 1 1; and

FIG. 13 is a sectional view taken along the line XIII- XIII of FIG. 11.

Proceeding next to the drawings where like reference symbols indicate the same parts throughout the various views a specific embodiment and modifications of the present invention will be described in detail.

The blade-wheel propeller as shown in FIG. 1 is mounted within a recess or well 2 fixedly mounted in the hull l of a ship and has rotatably mounted therein a wheel body 3 having a plurality of blades 4 pivotally mounted thereon. The wheel body 3 is driven by a prime mover 5 through a bevel gear transmission 6 with the prime mover being fixedly mounted in the ship.

On the top of the well 2 there is provided an upper part 7 having therein a bearing neck 8 to accommodate a bearing bush 9for the central spherical head of a control column 10. The lower end of the control column 10 is also provided with a sphere and is pivotally connected to a control disk 11 which is slidably positioned in the interior of the wheel body 3. The upper end of the control column 10 is also provided with a ball head which is pivotally connected to the slidable components of servo motors 12, 13. Each of the servo motors I2, 13 is provided with a control valve 14, 15 whose moveable member is actuated by means of a rectilinear motion transmission generally indicated at 17 in FIG. 2 and mounted within a propeller housing 16.

The rectilinear motion transmission 17 is mounted on two servo shafts 19, 20 which are rotatable journaled in a cover 18. The servo shaft 19 is coupled by a mechanical linkage 21 to a travelling control lever 24 on a control stand 23 which may be mounted on the bridge of the ship. The servo shaft 20 is similarly coupled through a mechanical linkage 22 with a steering wheel also mounted on the control stand 23. The mechanical linkage between the servo shafts 19 and 20 and the control stand 23 may be replaced by hydraulic, pneumatic or electrical connections.

The rectilinear motion transmission 17 may also be installed in the lower portion of the control stand 23 or in a separate housing in any other location in the ships hull 1 and may be coupled to the control valves 14, 15 of the servo motors 12, 13 of the blade-wheel propeller on one hand and to the steering wheel 25 or the travelling control lever 24 of the control stand 23 on the other hand by mechanical, hydraulic, pneumatic or electrical connections. In this construction, however, it is necessary for a corresponding return action to be provided between the control valves 14, 15 and the rectilinear motion transmission 17 positioned at a remote location.

In FIG. 2, there is illustrated a rectilinear motion transmission mechanism according to the present invention in a position in which the directiontforward and rearward) as well as the helm position has been selected. The transmission 17 is provided with a middle transmission link 34 upon which is mounted a first joint pin so as to be rectilinearly moveable. The pin 30 is in the center of the link 34 the ends of which are pivotally connected at 38, 39 to the two outer transmission links 32, 33. These transmission links form substantially a Z-shaped configuration. A radius rod 35 is also pivotally connected to the end of the outer transmission link 33. The transmission links 32, 33, 34 and the radius rod 35 are of equal length and arranged in parallel pairs. However, the lengths of the links 32, 33, 34 may also be diiferent and may differ from the length of the radius rod 35. Neither a direction of travel nor a direction of course is selected when the first pivot pin 30 is in its neutral position 0. In this position the axis of the pin-30 will coincide with the axis of rotation of the wheel body 3. In this neutral position, the angles between the outer transmissionlinks 32, 33 and the middle transmission link 34 and the angle with respect to the radius rod 35 in parallel thereto will be approximately The axes of the servo motors 12, 13 and their slidable pistons 62, 63 intersect at the axis of rotation of the wheel body and each of these pistons are connected to a bearing sleeve on the upper ball head of the control column 10 by means of a link not shown in the drawings which is pivoted by piston pins 66, 67 on piston rod heads 64, 65.

The rectilinear motion transmission 17 is pivotally suspended on the free end of the outer transmission link 32 which is fixedly connected to the servo shaft 19 for travelling in a forward or reverse direction and on the free end of the radius rod 35 which is fixedly connected to the servo shaft 20 for the rudder or change of course of the ship. The transmission 17 is thus suspended from the cover 18 of the propeller housing by the servo shafts 19 and 20. The servo shafts 19, 20 and accordingly the transmission link 32 and radius rod 35 respectively can be rotated from the control stand 23 in the directions indicated by the arrows shown in FIG. 2. When the rudder or helm control 25 and the radius rod 35 are retained in the neutral position and if the direction control lever 24 is adjusted, the first pivot pin 30 will move on a straight line 31. When the direction control lever 24 and the outer transmission link 32 remain in their stationary positions, the first pivot pin 30 will move transversely to the direction of the straight line 31 when the servo shaft 20 is rotated by means of the helm wheel 25.

Adjusting linkage 40 to 45 and 50 to 55 respectively for the control valves 14, 15 of the servo motors 12, 13 is pivotally connected to the first pivot pin 30. Links 40, 50 each have one end pivotally connected to the first pin 30 and the other end to levers 41, 51 and pivotal connections 60, 61 to the rockers 44, 54 which in turn are pivotally connected to the housing 49, 59 of the control valves 14, 15. The levers 42, 52 are of equal length and are connected to the levers 41, 51 by means of the outer pivotal connections 43, 53 which are remote from the connections of the levers 41, 51 with the links 40, 50. The other ends of the levers 42, 52 are pivotally connected to the piston pin 66, 67. Double links 45, 55 are positioned below the rockers 44, 54 and have their free ends connected by pins 46, 56 to the control pistons 47, 57 of the control valves 14, 15 the linkage as described above for connecting the control pistons 47, 57 to the first pivot pin 30 of the rectilinear motion transmission 1.7 are best seen by reference to FIG. 3.

As described above, the rectilinear motion transmission 17 is supported by the two servo shafts l9 and 20 in a cover top part 18 positioned on top of the propeller housing cover. If the cover 18 is circular and its center corresponds with the center of the circular opening closed by the cover and these coinciding centers coincide with the neutral position of the rectilinear movement of the pivot pin, it is then possible to adjust the direction of thrust for straight ahead travel merely by rotation of the cover 18. The forces and moments exerted by the rectilinear motion transmission on the cover 18 are small since they originate only from the linkage for adjusting the pilot control means. Frictional engagement between the cover 18 and the propeller housing is usually sufficient, at least during the trail period of the ship, in order to prevent any unintentional rotation of the cover 18. When the cover 18 has been adjusted to its optimum position with respect to the propeller housing the cover may then be secured with respect to the housing.

The linkage for guiding the first pivot pin precisely rectilinearly in the sliding zone of the control valves can be carried out by linkage which is conveniently accommodated in the propeller housing.

In the operation of the linkage demonstrated in FIGS. l-3, when the first pivot pin 30 is displaced because of rotation of either or both of the outer transmission link 32 and the radius rod 35 under the action of their respective servo shafts 19, 20, the pin 30 will be moved from the neutral position into a predetermined new position I. This movement of the pin 30 is accompanied by displacement and rotation of the links 40, 50 which are pivotally connected to it. The ends of the links 40, 50 connected to the levers 41, 51 are thus displaced from their normal positions into new positions and are pivoted. As a result, the pivotal connections 60, 61 located on the centers of the levers 41, 51

move along circular arcs whose centers are located at third pins 48, 58 mounted on the housings 49, 59 of the control valves 14, and whose radius is equal to the distance between the joints of the rockers 44, 54. Any motion of the first pivot pin 30 also varies the position of the outer joints 43, 53. Since the ends of the levers 42, 52 connected to the piston pins 66, 67 are initially retained in position by the pistons 62, 63 of the servo motors l2, 13, the outer joints 43, 53 will move along circular arcs with the axes of the piston pins 66, 67 as the centers and with the distances between the outer joints 43, 53 and the piston pins being the radii. The movement of the outer joints 43, 53 will cause the second joint pins 46, 56 by means of which the double links 45, 55 are connected to the control pistons 47, 57 to change their positions and thus displace the control pistons 47, 57 with respect to the housings of the control valves l4, 15. This movement of the control pistons 47, 57 causes hydraulic fluid to be supplied to the appropriate sides of the pistons 62, 63 of the servo motors 12, 13. The servo motors will thus move corresponding precisely to the motion of the first pivot pin 30 to displace the upper ball head of the control column 10. The ends of the levers 42, 52 pivotally connect to the piston pins 66, 67 will be displaced in the direction of motion of the pistons 62, 63. At the same time, the outer joints 43, 53 of the levers 42, 52 will move in accordance with the linkage 40, 41, 44 or 50, 51, 54 with the first pivot pin 30 and the third pins 48 and 58 functioning as fixed points. When the levers 42, 52 move as described above, the control pistons 47, 57 will return into the neutral position as soon as the pistons 62, 63 of the servo motors have displaced the upper ball head of the control column into a position corresponding to the position of the first pivot pin 30.

Experience has shown that a wheel-blade propeller whose blades oscillate during rotation of the propeller absorbs greater power and therefore imposes a heavier load on a prime mover the greater the helm angle at a given rotational speed of the propeller, pitch for the blades and a speed of the ship. In order to prevent adjustment of the helm from overloading the prime mover when it is fully loaded by propulsion, a multi-link correction transmission having a parallelogram joint has been interposed in the rectilinear motion transmission linkage as shown in FIGS. 4-7. p

The correction transmission is indicated generally at and comprises two links 71, 72 of equal length positioned in parallel when the transmission is in a neutral position. Two rocker levers 73, 74 each having three pivotal connections arranged in the shape of a triangle are connected by a coupling radius rod 75 or 76 respectively to the rectilinear motion transmission 17. The first coupling radius rod 75 acts on the pivotal connection between the outer link 32 and the middle link 34 and on a joint 77 of the first rocker lever 73. The second coupling radius rod 76 acts upon joint 78 of the second rocker lever 74. The two other joints 79, 80 of the second rocker lever 74 interconnect the two links 71,72.

The free end of link 71 is mounted on a servo shaft 81 which controls the forward or rearward direction of the ship. When the servo shaft 81 is actuated the rod 71 is rotated in the direction of the double ended arrow thereon. The pulse supplied from the travelling control lever on the control stand is transferred directly to the correction transmission 70 while the pulse from the helm wheel acts on the rectilinear transmission radius rod 35, mounted on the servo shaft 20, to rotate the radius rod 35 as indicated by the double ended arrow.

The free end of the second coupling radius rod 76 is connected at 83 to an angularly disposed extension arm 82 from the radius rod 35. In straight forward travel, the servo shaft 20 and the joints 78 and 83 of the second coupling radius rod 76 are disposed in a first plane which is perpendicular to a second plane defined by the joint 78 and the second stud 85 which suspends the correction transmission 70 on the cover part 18. This structure of the correction mechanism 70 positions the second coupling radius rod 76 in alignment with the extension arm 82 of radius rod 35 when the ship is travelling straight ahead. A force exerted by the correction transmission 70 on the second coupling radius rod 76 will not apply any torque on the radius rod 35. Instead, pivoting of the radius rod 35 by means of the second servo shaft 20 through the coupling radius rod 76 will transmit the largest possible torque for the given dimensions of the correction transmission 70 to be transmitted onto the second rocker lever 74 to influence the propeller pitch.

In the event of rotation of the second servo shaft 20 in any of the two possible directions of rotation, the second rocker lever 74 will always be rotated in the clockwise direction about the second stud 85 which is mounted in the cover top part 18, the angle of rotation increasing in accordance with the increase of angular deflection of the second servo shaft 20 and therefore of the radius rod 35. Rotation of the second rocker lever 74 about the second stud 85 results in a displacement of the joint 86 in the direction towards the rectilinear motion transmission 17, the said joint 86 connecting the second rocker lever 74 with the second rod 72 and, in the same way as the joint 77 which connects the first rocker lever 73 to the coupling radius rod 75, being disposed on the straight guide 31 when in the neutral position. Under these conditions, the joint 80, connecting the second rod 72 to the first rocker lever 73 will then be disposed on a circle whose center is formed by the position of the joint 86 disposed on a circle whose center is the stationary second stud 85. The position of the first rocker lever 73 is also defined by rotation of thefirst rod 71 by means of the first servo shaft 81. The rotation of the first rod 71 defines the location of the joint 79 by means of which the first rocker lever 73 is connected to the first rod 71. The locus of the third joint 77 of the aforementioned rocker lever 73 may be defined from the loci thus defined for the joints 79 and 80 of the first rocker lever 73. Irrespective of the direction in which the first rod 71 is rotated from the neutral position by operating the travelling control linkage, acting on the first servo shaft 81, the aforementioned locus will always be disposed more closely to the neutral position of the first pivot pin 30 than under conditions in which the second servo shaft 20, connected to the second control linkage for the rudder and, together therewith, theradius rod 35, the extension arm 82 and the coupling radius rod 76 are disposed in the neutral position. Accordingly, the cor rection transmission 70 fulfils the function of automatically reducing the propeller pitch when the helm is adjusted and of automatically restoring the propeller pitch to the original value when the control disc of the vertical-axis driving linkage is returned into the position corresponding to straight ahead travel.

The elevation illustrated in FIG. discloses in a manner similar to that disclosed in FIG. 3 the arrangement of the transmission parts of the rectilinear motion transmission 17 while the elevations of FIGS. 6 and 7 show the arrangement of the transmission parts of the correction transmission 70.

FIG. 8 shows the same control system as that of FIGS. 4 to 7, also along the sectional line IV-IV but with a setting which differs from that illustrated in FIGS. 4 to 7. In the last mentioned setting, the bladewheel propeller is set to the pitch F as well as to the helm angle G. The components F and G are referred to a system of Cartesian co-ordinates with the neutral position 0 of the first pivot pin 30 as the origin and with the straight guide 31 as the F axis. Accordingly,-and for this setting of the control system, the first pivot pin 30 will be disposed at a locus other than the neutral position 0 and will therefore be disposed outside the axis of rotation of the wheel member. Whether the components F and G plotted in FIG. 8 for a vertical-axis propeller installed in a ship correspond to ahead travel or astern travel or star-board rudder or port rudder depends on the manner in which these components are transferred to the control disc disposed in the wheel body of the blade-wheel propeller, on the construction of the driving linkage for ponent G plotted in FIG. 8 will also be obtained by counter-clockwise rotation of the radius rod 35, mounted on the second servo shaft 20.

Rotation of the rod 71 by means of the first servo shaft 81 results in a corresponding displacement of the joint 79 and therefore of the first rocker lever 73 whose joint 77, acting on the coupling radius rod 75, moves approximately on the straight guide 31 in the direction towards the neutral position 0 while the joint 38, mounted on the outer transmission element 32, is displaced in approximately the same direction on a circular arc whose center is the first stud 84.

Rotation of the radius rod 35 by means of the second servo shaft 20 causes the joint 37 of the outer transmission link 33 and the outer joint 39 of the middle transmission link 34 to be displaced along a line which is substantially perpendicular to the direction of the straight guide 31, provided this is associated with the travelling direction of the blade-wheel propeller for straight ahead travel. In this case, the distance F traversed by the first joint pin .30 in the direction towards the straight guide 31 will correspond to the selected travelling deflection and therefore to the propeller pitch while the displacement travel G traversed perpendicularly to the straight guide 31 will correspond to the intended helm deflection.

FIG. 9 shows the control system of FIG. 4 in a position in which the loci of the fixed joint axes, namely of the first servo shaft 81, the second servo shaft 20, the first stud 84 and the second stud are pivoted in the clockwise direction through an angle of approximately 14 about the neutral position 0 ofthe first joint pin 30 as center relative to the position shown in FIG. 8. The straight guide 31 of FIG. 8 will then assume the direction 31' of FIG. 9; it traverses through the neutral position of the first joint pin 30 and through the locus 38 A of the joint 38 associated with the middle transmission element 34. The above fixed joint axes will assume the positions 81 of the first servo shaft 81, the position 20' of the second servo shaft 20, the position 84' of the first stud 84 and the position 85' of the second stud 85. Simultaneous pivoting of all these joint axes by the same angular amount is obtained by virtue of the fact that the housing cover 16 of the top part 7 of the propeller housing is provided with a circular aperture of appropriate size and provided with a ring flange 91, the aforementioned fixed joint axes being disposed in a flat cover top part 18, adapted to close the aforementioned circular aperture 90, the said axes being located in eye holes of the cover top part. The eye hole 92 for accommodating the first stud 84' is shown in FIG. 10 while the eye holes provided in the cover top part 18 journalling the first servo shaft 81, the second servo shaft 20 and the second stud 85 are shown in FIGS. 5, 6 and 7. The central part of the cover top part 18 is also provided with a circular aperture which is reinforced with a ring insert 93 and closed with a plate 94 of transparent material. A pointer 95, mounted in the axis of the first joint pin 30 and indicating the deflection of the first joint pin 30 relative to its neutral position 0, marked on the plate 94 moves below said plate.

This construction of the correction transmission permits unobstructed operation of the travelling control lever from the neutral position into the full ahead or full astem position and permits a corresponding motion of the central control on the straight guide line defined by the two outer transmission links of the rectilinear motion transmission because one of the outer transmission links is stationarily supported in the propeller housing and the other pivots around a pivoting point of the radius rod the locus of which is maintained in one position when the rudder wheel is stationary. This is because the line through which the first coupling radius rod acts passes through the second servo shaft, connected to the rudder wheel, so that no torque is exerted by the said coupling radius rod on the rectilinear motion transmission radius rod mounted on the second servo shaft.

However, if the rudder wheel is moved while the central control disk is set to travelling and if, accordingly, the radius rod of the rectilinear motion transmission is pivoted, the coupling radius rod, hinged to the extension arm, will be pivoted from the stretched position, irrespective of the pivoting direction of the aforementioned radius rod; the coupling radius rod joint, connected to the first rocker lever, moves in the direction towards the second servo shaft for rudder operation and thus causes the first link pin, disposed on the middle of the middle transmission element, to be retracted towards the neutral position of said link pin. The extent of the aforementioned retraction of the first link pin will be the greater the further the direction of the coupling radius rod deviates from the stretched direction.

A construction with a disc cam may be used in place of the correction transmission described above and comprising levers and rods because by these means it is possible for the action of the correction transmission to be adapted in a particularly simple manner to different operating conditions, in particular different power characteristics of the prime mover for the blade-wheel propeller. It is merely necessary to exchange the disc for a disc cam adapted to changed engine characteristics. A control system of this kind is provided with a correction transmission, illustrated in FIGS. 11 to 13 which differs from that illustrated in FIGS. 4 to while a rectilinear motion transmission 117 is constructed substantially in accordance with the same principle as that of the rectilinear motion transmission 17 of FIGS. 4 to 10. In the rectilinear motion transmission 1 17, the thrust cylinders 97, 98 of the servo motors 12, 13 are provided with bearing heads 99, 100, 101. The bearing head 99 of the thrust cylinder 97 is constructed as a fiat plate which acts in the middle of the thrust cylinder 97 and centrally surrounds the bearing housing 102 of the upper ball head 103 associated with the control rod 10. The thrust cylinder 98 is provided with a pair of bearing heads 100, 101 which are disposed on both sides of the bearing head 99. The forces exerted by the two servo motors 12, 13 therefore act centrally on the upper ball head 103 of the control rod 10.

The pistons 62, 63 of the two servo motors 12, 13 are pivoted by means of the piston rods 68, 69 on the housing cover 16 of the propeller housing. Each thrust cylinder 97, 98 is slidably supported on a sliding surface 104 which is normally disposed horizontally and perpendicularly to the axis of rotation of the wheel member. The sliding surface 104 for the two thrust cylinders 97, 98 is disposed on the hollow conical structure 105 supporting the control column 10 and mounted on the housing cover 16.

The bearing housing 102 for the upper ball head 103 is provided with a circular cylindrical external surface 106. Accordingly, when the servo motors l2, 13 are operated, the bearing housing can slide in a corresponding bore 107 of the bearing heads 99, 100, 101 in the vertical direction without exerting any positive forces on to the bearing heads 99, 100, 101. It is therefore possible for the servo motors 12, 13 to be pivoted on the housing cover 16 by means of cylindrical piston pins 66, 67 because the thrust cylinders 97, 98 are displaced merely in a plane which is normal to the axis of rotation of the wheel body and the said thrust cylinders need not follow the motions of the upper ball head 103 in the direction of the axis of rotation. Furthermore, owing to this construction it is possible to avoid spherical joint motions in the rectilinear motion transmission 117 and in the correction transmission 170.

As can best be seen from FIG. 12, the top of the upper bearing head 100 has a cover 108 mounted on it which supports a hollow cylindrical trunnion 109, disposed coaxially relative to the bearing housing 102.

One end of each of two levers 111, 121, is rotatably journalled on the trunnion 109. The levers 111, 121 are parts of the traversing linkage 111 to of 121 to for the control valves 14, 15 of the servo motors l2, 13. Their construction and method of operation corresponds to that of the traversing linkage 40 to 45 or 50 to 55 for the control pistons 47, 57 illustrated in FIGS. 2 and 3.

Levers 112, 122 of identical length and of approximately the same shape as the levers 111, 121 are disposed above the levers 111, 121 and parallel thereto when the hollow cylindrical trunnion 109 is in the neutral position. The ends of the levers 111, 121 remote from the trunnion 109 are connected to the corresponding ends of the levers 112 or 122, respectively, by means of the outer joints 113 or 123 respectively. One end of a rocker 114, 124 is hinged in the middle of each of the levers 111, 121, the other end of I said rocker having the control piston 47 or 57 of the control valve 14 or 15 respectively pivoted to it. One end of a further rocker 1 15 or 125 of the same length as the rocker 114 or 124 respectively is pivoted to the middle of each of the levers 1 12, 122. The other end of the rocker 115 or 125, respectively, is pivotally connected to a bracket 119 or 129 respectively which is mounted on the housing of the control valves 14 or 15, respectively.

The ends of the levers 112 or 122 respectively disposed at a distance from the outer joints 113, 123 are expanded into an eyelet which rotatably surrounds the first pivot pin, constructed as hollow pin 130. When the control system is in the neutral position, the hollow pin 130 is coaxial with the hollow cylindrical trunnion 109 but when the control linkage is operated from the control stand it is displaced relatively thereto and traversely to the axis of rotation of the wheel member.

'Tothis end, the hollow cylindrical trunnion 109 is covered directly above the levers 111, 121 by means of a flat plate 118, provided on its top side with a sliding surface which is not shown, said plate being mounted by means of a pointer pin 116 on the cover 108. The inner diameter of the hollow pin 130 is sufficiently large so that even with the greatest deflection thereof relative to the hollow cylindrical trunnion 109 owing to a travelling control lever adjustment from the control stand from full ahead to full astern or vice versa and/or if a hard to helm position is selected with the steering wheel there will be no physical contact between the internal surface of the hollow pin 130 and the external surface of the pointer pin 116 which is threaded into the central portion of the cover 108.

The hollow pin 130 is provided with a flanged base 131 having a planar undersurface. The radial extension of said base 131 as measured from the internal surface of the hollow pin 130 is greater than half the stroke displacement of the control piston 47, 57 so that the undersurface of the base 131 still bears all round on the sliding surface of the plate 118 even if the stroke displacement of the control piston 47, 57 is fully utilized. In order to avoid the hollow pin 130 being lifted off the plane plate 118 and thus to avoid any canting in the rectilinear motion transmission 117, the upper edge 1320f the hollow pin 130 is secured by a retaining plate 128 which is also mounted on the pointer pin 1 16.

The following parts of the transmission, being freely rotatable relative to each other, are disposed on the cylindrical middle part of the hollow pin 130 which extends between the base 131 and the upper edge 132; first the levers 112, 122, above thereof the coupling radius rod 126 and at the top the middle transmission element 134 which is constructed as an equal arm straight lever whose middle part surrounds the hollow pin 130. Two transmission links 32, 33 respectively, one each are hinged by means of the joints 38, 39 on the two ends of the middle transmission link 134 so that when the hollow pin 130 is in the neutral position, the two outer transmission links 32, 33 are disposed at right angles to the line connecting the two joints 38 and 39. In this embodiment, the direction of the middle transmission link 134 extends at an angle to the axes of the servo motors 12, 13 namely, in the direction of the straight guide 31 when said servo motors are in the neutral position, the straight guide being associated with the straight ahead direction of the ship. The free ends of the two outer transmission links 32, 33 are also pivotally connected to the first stud 84 or to the joint 37 on the radius rod 135. The distance between the first stud 84 and the joint 38 is the same as the distance between the joint 37 and the joint 39 of the middle transmission link 134 and approximately equal to the distance between the two joints 38 and 39 of the middle transmission link 134. In this embodiment, the first stud 84 and the joint 37 is disposed in the vertical median plane of the servo motor 12 when the hollow pin 130 is in the neutral position.

When the hollow pin 130 is in the neutral position,

the radius rod135 is disposed in parallel to the middle transmission link 134 and mounted on the second servo shaft 20, which is rotatably journalled in the cover top part 18 and is rotated by the steering wheel of the control stand. Any motion of the second servo shaft 20 is accompanied by operation of the correction transmission 170 by means of which the pitch of the vertical axis propeller is reduced when the helm angle is adjusted.

To this end, and as seen most conveniently by reference to FIG. 13, a correction lever 137 with a cam track 136 is mounted in addition to the radius rod on the second servo shaft 20 rotation of which is accompanied by rotation in the same sense and by the same amount of the correction lever 137. A takeoff roller 139, rotatably joumalled in a double radius rod 138, rolls on the cam track 136. A powerful tension spring 142 is stressed between the roller pin 140,

mounted in the double radius rod 138 and supporting the take-off roller 139 and a retaining stud 141 which is mounted in the correcting lever 137.

The double radius rod 138, comprising two individual radius rods which are disposed at a distance slightly exceeding the width of the take-off roller 139, is pivotably supported by its end nearest to the take-off roller 139 and directed against the hollow pin 130 by means of a second stud 85 which is mounted in the cover top part 18. The distance between the roller pin and and the second stud 85 amounts to approximately one-fifth of the length of the double radius rod 138. When the hollow pin 130 is in the neutral position, the double radius rod 138 will be positioned in parallel to the coupling radius rod 126, to "the middle transmission link 134 and therefore also to the radius rod 135. The end of the double radius rod 138 which is removed from the take-off roller 139 by a greater distance is pivotally connected by means of a rod 145 to that bifurcated end 127 of the coupling radius rod 126, disposed at a distance from the hollow pin 130, the rod 145 being positioned in parallel to the two outer transmission links 32, 33 and to the correction lever 137 when the hollow pin 130 is in the neutral position. A sliding block 146 is pivotably supported in the bifurcated end 127 of the coupling radius rod 126 and is adapted to slide on a rail 147 which is disposed parallel to the rod 145 when the hollow pin 130 is in the neutral position. The rail 147, constructed, for example as a cylindrical rod, is mounted on the first servo shaft 81, connected to the travelling control lever of the control stand and being rotatably mounted in the cover top part 18, said rod being adapted to pivot into one or the other direction when the travelling control lever is adjusted. To prevent the motion of the sliding block 146 on the rail being obstructed by the first servo shaft 81 when the travelling lever and steering wheel perform a large deflection, one end of the rail 147 is inserted and pinned into a precisely fitting bore of an angle piece 143 which is mounted on the-lower end of the first servo shaft 81.

In a manner similar to that of the correction transmission 70 illustrated in FIGS. 4 to 7, the correction transmission reduces the distance between the appropriate location of the hollow pin 130 and its neutral position if for a given propeller blade pitch, selected by an appropriate setting of the travelling control lever, the steering wheel of the control stand is operated in one or the other direction of rotation.

The operation of the aforementioned correction transmission 170 is as follows:

When the steering wheel 25 on the control stand is operated, the second servo shaft is pivoted to the right or left by a defined angular amount to produce a corresponding motion of the elements of the rectilinear motion transmission 117 and of the hollow pin 130. The hollow pin 130 is thus displaced into a position corresponding to the deflections of the joints 37 and 39. At the same time, rotation of the second servo shaft 20 causes the correction lever 137 to be pivoted along its cam track 136 which is disposed at the further end from the second servo shaft 20. When the correction lever 137 is pivoted, the cam track 136, being constructed as a semi-circle with approximately the same diameter as the take-off roller 139 and under the action of the tension spring 142, will rotate the double radius rod 138 in the counter-clockwise, direction (see FIG. 11) about the second stud 85 as axis of rotation. Irrespective of the direction of rotation of the second servo shaft 20, rotation of the double radius rod 138 will move the rod 145 to the right. Since it is pivoted to that end of the double radius rod 138 which is disposed at a distance from the second stud 85 so that the coupling radius rod 126, pivoted on the left hand end of the aforementioned rod 145 by means of the joint 144 is rotated in the counter-clockwise direction about the hollow pin 130. At the same time, motion of the rod 145 causes the block 146, supporting the journals of the joint 144, to be moved to the right on the rail 147.

When the travelling control lever 24 is fixedly adjusted and the first servo shaft 81 is therefore non-rotationally retained, the angle piece 143 and therefore the sliding rail 147 will remain in the previously described direction which is perpendicular to the straight guide 31. If the second servo shaft 20 is rotated, the motion of the sliding block 146 on the sliding rail 147 and therefore the displacement of the hollow pin 130'initiated through radius rod 135 and transmission elements 33, 134 perpendicularly to the straight guide 31 will be limited. If only the travelling control lever of the control stand is operated and therefore, while the second servo shaft 20 is retained in the stationary position, the angle piece 143 and together therewith the sliding rail 147 is rotated from its position which is perpendicular to the straight guide 31 and the blade-wheel propeller will thus be pitched. If the helm is altered by rotation of the second servo shaft 20 while the blade-wheel propeller is set to a pitch, the tension spring 142 will pull the rod 145 and therefore the sliding block 146 as well as the end 127 of the coupling radius rod 126 on the slide rail 147 towards the first servo shaft 81 and thus move the hollow pin 130 closer to its neutral position. The propeller pitch will be accordingly reduced.

The extent of propeller pitch reduction required in relation to the extent of the selected rudder position can be adapted to the characteristics of the prime mover by suitable construction of the cam track 136 as well as by appropriate selection of the dimensions for the transmission parts of the correction transmission 170, in particular, the lever ratio of the double radius rod 138. When the hollow pin 130 is in the neutral position, the sliding rail 147 may be disposed out of parallel relative to the outer transmission links 32, 33 in order to prevent slight deflection of the hollow pin 130 in the direction of the straight guide 31 when the second servo shaft 20 is rotated.

The embodiments of the control system according to FIGS. 2 to 13 relate to blade-wheel propellers in which the position of the first pivot pin 30 or of the hollow pin relative to the neutral position in full ahead travel and the position of the first pivot pin 30 or of the hollow pin 130 in relation to the neutral position in full astern travel are offset relative to each other by precisely In some cases it may be desirable that the position of the first pivot pin 30 or of the hollow pin 130 in relation to the neutral position in full ahead travel and full astern travel is offset by an angle which differs from 1 80".

It is not necessary that the rectilinearly guided pivot pin mounted on the middle transmission link of the rectilinear motion transmission is disposed precisely on the axis of rotation of the propeller when the system is in the neutral position. Occasionally it may be advantageous if the rectilinear motion transmission together. with the correction transmission be installed outside the propeller at any location of the ship, for example, in the sub-structure of the control stand. In this case, however, it is necessary that in addition to the mechanical, hydraulic, pneumatic or electric means for connecting the travelling control lever and the rudder wheel to the propeller, two further such connections are provided as return linkage for the control valves. In dispensing with a mechanical connection between the control stand and the propeller and instead using one of the other connecting means, it is also possible to eliminate the rectilinear motion transmission together with the correction transmission and for the servo motor control valve settings associated with the desired adjustments of the travelling control lever and the steering wheel to be supplied from a data processing system.

As will be apparent from the above disclosure, the construction of the control system according to the invention avoids the disadvantages of the previous embodiments and in addition offers the following additional advantages namely:

It is possible for the blade-wheel propeller to be constructed without reference to the direction of the drive shaft relative to the longitudinal orientation of the ship and therefore to be able to use uniform drawings and other manufacturing specifications for all propellers of the same construction and, moreover, for propellers of the most common designs and sizes to be manufactured for inventory. To adapt such a propeller to the appropriate installation conditions it is merely necessary during assembly or, where appropriate only in the course of trials of the ship, for the cover top part to be secured in the optimum position for straight ahead travel irrespective of the orientation of the driving shaft. By being able to use pre-fabricated propellers from stock for installation substantially reduces the building time of a ship because this was previously substantially defined by the delivery time for the bladewheel propeller. The manufacture of blade-wheel propellers may be confined to a few standard types so that a substantial cost saving may also be achieved.

The reduction of the blade pitch, defined by the amount of displacement of the first joint pin from its neutral position, can be achieved in particularly advantageous manner when the helm angle is adjusted with embodiments illustrated in FIGS. 11 to 13 by appropriate construction of the cam track because, if necessary, this can be subsequently altered or replaced on the completely installed blade-wheel propeller. The operating characteristics of the blade-wheel propeller can thus be precisely adapted to those of the prime mover.

It is understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within the invention as may fall within the scope of the appended claims.

What is claimed is:

1. In a control system for a ship blade-wheel propeller, the combination of a propeller housing, a disk-shaped wheel body rotatably mounted in said housing and having a plurality of blades extending vertically downwardly adjacent the periphery thereof, said blades being pivotable about their longitudinal axes, an adjustable central control disk within said wheel body, linkage means interconnecting said blades with said control disk whereby the blades are oscillated during each revolution of the wheel body, the deflection of the blades during their oscillatory movements being defined by the distance between the axis of rotation of the wheel body and the center of the control disk, the oscillations of the blades producing a thrust in a direction perpendicular to a plane passing through the axis of rotation of the wheel body and the center of the control disk, a control column mounted for universal tilting movement and having its lower end pivotally connected to said control disk, a pair of servo-motors on said propeller housing at right angles to each other and pivotally connected to said column to displacethe ends of the column transversely to the axis of rotation of the propeller, pilot control means actuable from a remotely located control stand for operating said servomotors, the improvement of a first pivotable servo shaft operatively connected to said pilot control means, rectilinear motion transmission means including a first pivot pin on a rectilinearly guided portion thereof and connected to said first servo shaft, a second servo shaft operatively connected to said pilot control means, a radius rod pivotally connecting said rectilinear motion transmission means and said second servo shaft, and means responsive to the position of said first pivot pin for operating said servo motors.

2. In a control system as claimed in claim 1 and comprising correction transmission means for connecting said rectilinear motion transmission means to said first servo shaft.

3. In a control system as claimed in claim 1 wherein said rectilinear motion transmission means is supported within said propeller housing or within a structural component which can be attached thereto by said first and second servo shafts.

4. In a control system as claimed in claim 1 wherein said rectilinear motion transmission means comprises a first link attached to said first servo shaft, a second link pivotally connected at one end thereof to said first link, a third link pivotally connected to the other end of said second link and said three links being disposed in substantially a Z-shaped configuration with said first and third links being equal in length and substantially parallel to each other when the control system is in its neutral position, said first pivot pin being positioned at -l the center of said second link equidistantly from the pivotal connections as both ends thereof.

5. In a control system as claimed in claim 4 wherein said first and third links are substantially perpendicular to said second link when the control system is in its neutral position.

6. In a control system as claimed in claim 4 and comprising correction transmission means pivotally connected to said second link and said radius rod and having a plurality of links interconnected at pivot points positioned to define a parallelogram, said correction transmission means moving the central control disk to its neutral position along an approximately elliptical path from a position in which the ship is travelling on a straight course when the pilot control means is actuated to cause the ship to turn.

7. In a control system as claimed in claim 6 wherein said correction transmission means comprises first and second rods each having pivotal connections on both ends thereof, first and second rocker levers each having three pivotal connections thereon defining a triangle, a first extension on said radius rod, said second rocker lever being pivotally mounted on said propeller housing and pivotally connected to said first extension by a first coupling radius rod the pivotal connection on said first coupling radius rod being disposed in a first plane passing through said second servo shaft when the rectilinear motion transmission means is in its neutral position, the pivotal connection on said second rocker lever and said first coupling radius rod being disposed in a second plane passing through. the pivotal connection of said second rocker lever on said propeller housing and perpendicular to said first plane, said second rocker lever and first coupling radius rod pivotal connection also being disposed in a third plane passing through the pivotal connection on said first rocker lever and said first and second rods, said first and second rods being parallel to said first and third links of said rectilinear motion transmission means, and a second coupling radius rod pivotally connecting said first rocker lever to said second link at its connection to said first link.

8. In a control system as claimed in claim 6 wherein said correction transmission means comprises a hollow first pivot pin, a correction lever fixedly mounted on said second servo shaft and having a cam track thereon, a double radius rod having one end pivotally connected to the propeller housing and having a roller thereon urged into engagement with said cam track, a rail fixedly mounted on said first servo shaft, a block slideably mounted on said rail, a rod pivotally connecting said block to the other end of said double radius rod, said rail and rod being substantially parallel to the first and third links of the rectilinear motion transmission means and to a line passing through said second servo shaft and said roller, said rail and rod being aligned when the rectilinear motion transmission means is in the neutral position, and coupling radius rod means pivotally connecting said sliding block to said hollow first pivot pin and lined with said second link when the control system is in its neutral position.

9. In a control system as claimed in claim 3 wherein those elements mountable on said propeller housing or a structural component which can be attached thereto are mounted on a cover member of said propeller housneutral position. 

1. In a control system for a ship blade-wheel propeller, the combination of a propeller housing, a disk-shaped wheel body rotatably mounted in said housing and having a plurality of blades extending vertically downwardly adjacent the periphery thereof, said blades being pivotable about their longitudinal axes, an adjustable central control disk within said wheel body, linkage means interconnecting said blades with said control disk whereby the blades are oscillated during each revolution of the wheel body, the deflection of the blades during their oscillatory movements being defined by the distance between the axis of rotation of the wheel body and the center of the control disk, the oscillations of the blades producing a thrust in a direction perpendicular to a plane passing through the axis of rotation of the wheel body and the center of the control disk, a control column mounted for universal tilting movement and having its lower end pivotally connected to said control disk, a pair of servo-motors on said propeller housing at right angles to each other and pivotally connected to said column to displace the ends of the column transversely to the axis of rotation of the propeller, pilot control means actuable from a remotely located control stand for operating said servo-motors, the improvement of a first pivotable servo shaft operatively connected to said pilot control means, rectilinear motion transmission means including a first pivot pin on a rectilinearly guided portion thereof and connected to said first servo shaft, a second servo shaft operatively connected to said pilot control means, a radius rod pivotally connecting said rectilinear motion transmission means and said second servo shaft, and means responsive to the position of said first pivot pin for operating said servo motors.
 2. In a control system as claimed in claim 1 and comprising correction transmission means for connecting said rectilinear motion transmission means to said first servo shaft.
 3. In a control system as claimed in claim 1 wherein said rectilinear motion transmission means is supported within said propeller housing or within a structural component which can be attached thereto by said first and second servo shafts.
 4. In a control system as claimed in claim 1 wherein said rectilinear motion transmission means comprises a first link attached to said first servo shaft, a second link pivotally connected at one end thereof to said first link, a third link pivotally connected to the other end of said second link and said three links being disposed in substantially a Z-shaped configuration with said first and third links being equal in length and substantially parallel to each other when the control system is in its neutral position, said first pivot pin being positioned at the center of said second link equidistantly from the pivotal connections as both ends thereof.
 5. In a control system as claimed in claim 4 wherein said first and third links are substantially perpendicular to said second link when the control system is in its neutral position.
 6. In a control system as claimed in claim 4 and comprising correction transmission means pivotally connected to said second link And said radius rod and having a plurality of links interconnected at pivot points positioned to define a parallelogram, said correction transmission means moving the central control disk to its neutral position along an approximately elliptical path from a position in which the ship is travelling on a straight course when the pilot control means is actuated to cause the ship to turn.
 7. In a control system as claimed in claim 6 wherein said correction transmission means comprises first and second rods each having pivotal connections on both ends thereof, first and second rocker levers each having three pivotal connections thereon defining a triangle, a first extension on said radius rod, said second rocker lever being pivotally mounted on said propeller housing and pivotally connected to said first extension by a first coupling radius rod the pivotal connection on said first coupling radius rod being disposed in a first plane passing through said second servo shaft when the rectilinear motion transmission means is in its neutral position, the pivotal connection on said second rocker lever and said first coupling radius rod being disposed in a second plane passing through the pivotal connection of said second rocker lever on said propeller housing and perpendicular to said first plane, said second rocker lever and first coupling radius rod pivotal connection also being disposed in a third plane passing through the pivotal connection on said first rocker lever and said first and second rods, said first and second rods being parallel to said first and third links of said rectilinear motion transmission means, and a second coupling radius rod pivotally connecting said first rocker lever to said second link at its connection to said first link.
 8. In a control system as claimed in claim 6 wherein said correction transmission means comprises a hollow first pivot pin, a correction lever fixedly mounted on said second servo shaft and having a cam track thereon, a double radius rod having one end pivotally connected to the propeller housing and having a roller thereon urged into engagement with said cam track, a rail fixedly mounted on said first servo shaft, a block slideably mounted on said rail, a rod pivotally connecting said block to the other end of said double radius rod, said rail and rod being substantially parallel to the first and third links of the rectilinear motion transmission means and to a line passing through said second servo shaft and said roller, said rail and rod being aligned when the rectilinear motion transmission means is in the neutral position, and coupling radius rod means pivotally connecting said sliding block to said hollow first pivot pin and lined with said second link when the control system is in its neutral position.
 9. In a control system as claimed in claim 3 wherein those elements mountable on said propeller housing or a structural component which can be attached thereto are mounted on a cover member of said propeller housing which is coaxial with respect to said first pivot pin when the rectilinear motion transmission means is in its neutral position. 